I have a 420sel. Assuming it is the same, the fuse box is under the hood near the back right of the engine. It is about 8 inches by 12 inches and has a snap lock lid. Looking at the front of the vehicle the fuse box would be in front of the driver .
The starter relay is located on the battery side of the Mercedes 450SEL. It is close to the battery itself.
it is in the boot/trunk on the back left
Its under the car next to the gas tank
remove rotor from Mercedes 450sel?
the battery is under the hood by the windshield on the passenger side,
The 1978 Mercedes-Benz 450 starter relay switch can be found on the firewall in the engine compartment. The starter relay switch will be on the drivers side of the firewall.
i found the factory folded up guide for the fuses in the fuse box located on the driver's side.
on my Mercedes c180 2002 the spare fuses are found with the spare wheel in the boot in a tool kit.
The horn fuse, for your Mercedes ML 320, can be found in the fuse box in the engine compartment. A diagram of the fuses will be on the inside of the fuse box cover.
I have a 1988 420sel. I'm not sure if they are the same but I have a slide switch just to the right of the overhead light between the sun visors.
i have fuses for a Mercedes 2002 s500
The headlight fuse, on your Mercedes-Benz, is located in the fuse box. A location diagram of the fuses can be found on the inside cover of the fuse box.